Impact of mandatory indications for outpatient antibiotic orders on accurate tracking of antibiotic indications

OBJECTIVE

We sought to evaluate whether implementing mandatory indications for outpatient electronic antibiotic orders or using encounter International Classification of Diseases, Tenth Revision (ICD10) codes more accurately reflected clinicians' charted diagnosis in encounter notes. Secondarily, we examined the appropriateness of antibiotic prescriptions.

DESIGN

Cross-sectional study.

METHODS

Mandatory indications were added to all outpatient electronic antibiotic orders on May 18, 2022. A randomly selected convenience sample of 1300 outpatient encounters with antibiotics from walk-in clinics was reviewed. Adjusted logistic regression was used to compare the congruence between encounter ICD10 code and charted diagnosis for encounters from July 15 to September 15, 2021 (pre-implementation period) to the congruence between encounter ICD10 code, charted diagnosis, and mandatory indication for encounters from July 15 to September 15, 2022 (post-implementation period). Antibiotic appropriateness based on charted diagnosis was also evaluated.

RESULTS

Among 1300 outpatient encounters, congruence between charted diagnosis and ICD10 code significantly increased in the post-implementation period (87.7% (565/644)) versus pre-implementation (83.3% (540/648), adjusted odds ratio (aOR) 1.52; 95% CI 1.03-2.25). Congruence between charted diagnosis and mandatory indication during post-implementation was 95.2% (613/644) and >5 times more likely to be congruent than charted diagnosis and ICD10 code during pre-implementation (aOR 5.45; 95% CI 3.26-9.11). Antibiotic prescribing based on charted diagnosis was twice as likely to be appropriate in the post-implementation period (aOR1.99; 95% CI 1.32-2.98).

CONCLUSIONS

Mandatory indications within antibiotic orders show better congruence with charted diagnosis than ICD10 codes and may increase antibiotic appropriateness and congruence between ICD10 code and charted diagnosis.

A qualitative assessment of nonclinical drivers of pediatric outpatient antibiotic prescribing: The importance of continuity

BACKGROUND AND OBJECTIVES

Antibiotic overuse is common in outpatient pediatrics and varies across clinical setting and clinician type. We sought to identify social, behavioral, and environmental drivers of outpatient antibiotic prescribing for pediatric patients.

METHODS

We conducted semistructured interviews with physicians and advanced practice providers (APPs) across diverse outpatient settings including pediatric primary, urgent, and retail care. We used the grounded theory constant comparative method and a thematic approach to analysis. We developed a conceptual model, building on domains of continuity to map common themes and their relationships within the healthcare system.

RESULTS

We interviewed 55 physicians and APPs. Clinicians across all settings prioritized provision of guideline-concordant care but implemented these guidelines with varying degrees of success. The provision of guideline-concordant care was influenced by the patient-clinician relationship and patient or parent expectations (relational continuity); the clinician's access to patient clinical history (informational continuity); and the consistency of care delivered (management continuity). No difference in described themes was determined by setting or clinician type; however, clinicians in primary care described having more reliable relational and informational continuity.

CONCLUSIONS

Clinicians described the absence of long-term relationships (relational continuity) and lack of availability of prior clinical history (informational continuity) as factors that may influence outpatient antibiotic prescribing. Guideline-concordant outpatient antibiotic prescribing was facilitated by consistent practice across settings (management continuity) and the presence of relational and informational continuity, which are common only in primary care. Management continuity may be more modifiable than informational and relational continuity and thus a focus for outpatient stewardship programs.

Operationalising outpatient antimicrobial stewardship to reduce system-wide antibiotics for acute bronchitis

BACKGROUND

Antibiotics are not recommended for treatment of acute uncomplicated bronchitis (AUB), but are often prescribed (85% of AUB visits within the Veterans Affairs nationally). This quality improvement project aimed to decrease antibiotic prescribing for AUB in community-based outpatient centres from 65% to <32% by April 2020.

METHODS

From January to December 2018, community-based outpatient clinics' 6 months' average of prescribed antibiotics for AUB and upper respiratory infections was 63% (667 of 1054) and 64.6% (314 of 486) when reviewing the last 6 months. Seven plan-do-study-act (PDSA) cycles were implemented by an interprofessional antimicrobial stewardship team between January 2019 and March 2020. Balancing measures were a return patient phone call or visit within 4 weeks for the same complaint. Χ² tests and statistical process control charts using Western Electric rules were used to analyse intervention data.

RESULTS

The AUB antibiotic prescribing rate decreased from 64.6% (314 of 486) in the 6 months prior to the intervention to 36.8% (154 of 418) in the final 6 months of the intervention. No change was seen in balancing measures. The largest reduction in antibiotic prescribing was seen after implementation of PDSA 6 in which 14 high prescribers were identified and targeted for individualised reviews of encounters of patients with AUB with an antimicrobial steward.

CONCLUSIONS

Operational implementation of successful stewardship interventions is challenging and differs from the traditional implementation study environment. As a nascent outpatient stewardship programme with limited resources and no additional intervention funding, we successfully reduced antibiotic prescribing from 64.6% to 36.8%, a reduction of 43% from baseline. The most success was seen with targeted education of high prescribers.

141. Rapid Reduction in Concomitant Vancomycin and Piperacillin-tazobactam Use: A Model for Future Antimicrobial Stewardship Interventions

Background

Concomitant vancomycin and piperacillin-tazobactam use (CVPTU) for >2 days is associated with increased nephrotoxicity. At Vanderbilt University Medical Center, a sustained decline in CVPTU was achieved. A retrospective review of CVPTU and antimicrobial stewardship (AS) interventions was performed to develop a model for future AS quality improvement (QI) initiatives.

Methods

Data for adults receiving CVPTU January 2015 - August 2019 were extracted. No patients were excluded. Change in monthly incidence of CVPTU >2 days in relation to AS interventions was the primary outcome. CVPTU was analyzed with statistical process control (SPC) charts (QI Macros 2019). AS interventions were amassed from AS emails, meeting minutes, presentations and patient-specific interventions. We created a new intervention evaluation tool using the Hierarchy of Effectiveness (1-Education, 2-Policy, 3-Reminders, 4-Simplification, 5-Automation, 6-Forced Function) and a self-designed scale of impact (1-divisional subgroup, 2-division, 3-department, 4-center-wide). Scores were summed for each 6-month period and rated as low, moderate or high intervention strength. Periods were mapped against their corresponding CVPTU rate (Figure 1).

Results

CVPTU Data: During periods 1–5 (January 2015 - February 2018), an average 4% of admitted patients received >2 days CVPTU, decreasing to < 1% from period 5 (March 2018) onward (Figure 1). From period 1–5, an average 52.8% of patients with CVPTU received >2 days and dropped to 41.3% from period 5 onward (Figure 2).

Intervention Data: There was 1 low, 3 moderate and 4 high intensity periods. Intensity decreased as initiatives transitioned from behavior change to sustained behavior (Figure 1). The main interventions were education and patient-specific feedback. Division-specific antibiotic algorithms and computerized order sets re-enforced behavior. Infectious diseases consults and team pharmacists embedded the concept in daily practice.

Figure 1: Proportion of All Admissions with Concomitant Vancomycin and Piperacillin-Tazobactam Use (CVPTU) for >2 Days Mapped Against Simultaneous Quality Improvement Interventions.

Figure 2: Proportion of Patients with Concomitant Vancomycin and Piperacillin-Tazobactam Use (CVPTU) for >2 Days.

Conclusion

Persistent, repetitive center-wide intervention is key to driving and sustaining change. More analysis of specific intervention types and impact of external factors would enhance understanding and future use of this AS change implementation model.

Disclosures

All Authors: No reported disclosures

222. Comparison of Outpatient Antibiotic Prescriptions in a High Prescribing State, 2016–2018

Background

About 80% of antibiotic prescriptions are written in outpatient settings. Outpatient antibiotic use (AU) is highest in the Southern United States. Tennessee consistently has one of the highest AU rates in the country. Previous analyses found that 1,195 prescriptions were filled in Tennessee per 1,000 total population in 2016. Moreover, 50% of all outpatient antibiotic prescriptions were written by 9.3% of prescribers. We sought to assess Tennessee outpatient antibiotic prescribing trends, comparing 2016 with 2018 data.

Methods

The Tennessee IQVIA outpatient antibiotic prescription dataset from January 1 to December 31, 2018 was analyzed and compared to 2016 results. Orally administered antibacterial agents were included. Patients < 20 years old were classified as pediatric. County level population data were obtained from the Tennessee Department of Health. Antibiotic prescription rates were calculated as antibiotics prescribed per 1,000 population in the specified age group. Analysis was performed using SAS 9.4.

Results

The statewide AU rate decreased from 1,195 in 2016 to 1,074 in 2018 per 1,000 population. Consistent with the previous analysis, female patients (1,288), those over 65 years (1,459), and those < 2 years (1,372) had the highest rates of AU in 2018. Lower rates were observed in all age groups in 2018 except for the 3–9 years group. While narrow penicillins and macrolides remain the most frequently prescribed antibiotics, amoxicillin-clavulanate and ciprofloxacin fell out of the top five antibiotics used in adults, and amoxicillin-clavulanate fell out of the top five antibiotics used in pediatrics. Similar to 2016, 9.2% (3,098) of the providers contributed to 50% of the total prescriptions in 2016, and 2,090 of the 2,994 (69.8%) 2016 highest prescribing providers were also among the highest prescribers in 2018.

Conclusion

Despite a decline in outpatient antibiotic prescription volume, Tennessee remains one of the nation’s highest prescribing states. While a decline in broad spectrum antibiotic prescriptions may indicate a shift to more appropriate usage, these data do not include indication, excluding appropriate use assessment. Identifying and focusing antibiotic stewardship interventions for consistently high prescribers remains a priority for Tennessee.

Disclosures

All Authors: No reported disclosures

1130. Optimizing Use of COVID-19 Personal Protective Equipment among Resident Physicians at a Veterans Affairs Hospital

Background

Correct personal protective equipment (PPE) use is key to prevent infection. Observations on a single unit at the Veterans Affairs (VA) Tennessee Valley Healthcare System (TVHS) prior to COVID-19 (October 2019-February 2020) showed low rates of correct PPE use among healthcare workers (HCWs) (Figure 1). In response to the COVID-19 epidemic, the VA implemented new PPE protocols. Based on our initial observations, we were concerned that incorrect use of PPE may increase the risk of COVID-19 exposure among HCWs. Resident physicians, who work at many sites, may be at high-risk for incorrect PPE use due to rapid turnover and limited site-specific PPE training. We aimed to assess and improve COVID-19 PPE use among internal medicine residents rotating at the VA TVHS.

Figure 1: Pre-COVID-19 Observations of Adherence to Contact Precaution Protocols at the Veterans Affairs Tennessee Valley Healthcare System

Methods

We used the plan, do, study, act (PDSA) model. Prior to starting VA rotations, residents were emailed PPE education to review. We implemented a 1-hour video conference PPE protocol review at rotation start followed by in-person PPE use evaluations for residents performed by infectious diseases fellows on day 2 and day 5-6 post-review to provide just-in-time educational intervention. Errors at each PPE don/doff step were tracked. Correct PPE use data from both observations were compared using McNemar’s test. Baseline and post-implementation resident surveys assessed PPE use knowledge and comfort.

Results

Pre-implementation survey response rate was 72% (21/29); 19/21(91%) reported knowing which PPE to use and 16/21(76%) reported knowing how to safely don/doff PPE. Twenty of 29 (69%) residents completed both observations. Errors decreased by 55% (p=0.0045) from 17/20 (85%) to 6/20 (30%) between initial and follow up observations. Errors in hand hygiene, inclusion of all donning/doffing steps, and PPE reuse decreased, but PPE don/doff order errors increased (Figure 2). Post-project survey response rate was 16/29 (55%). All 16 reported knowing which PPE to use and how to safely don/doff PPE, and 11/16 (69%) residents felt both online and in-person interventions were helpful.

Figure 2: COVID-19 PPE Errors and Correction Types by Observation

Conclusion

Correct COVID-19 PPE use is essential to protect HCWs and patients. Just-in-time education intervention for PPE training may yield higher correct use compared to pre-recorded or online training.

Disclosures

All Authors: No reported disclosures

The neuroleptic chlorpromazine inhibits the cationic and stimulates the anionic phospholipid precursor synthesis in human lymphocytes

The widely used neuroleptic drug chlorpromazine (CPZ) influences membrane functions at the levels of ionic channels and receptors as shown. Here we show the effect of short term treatments by CPZ (30 microM), on the nucleotide-containing phospholipid precursors in human lymphocyte primary cultures. During 60 minutes incubation of the cells, the CDP-ethanolamine (CDP-EA) content was only slightly reduced (87 to 76 pmol/10(6) cells), the amount of CDP-choline (CDP-Ch) was inhibited totally (from 25 to 0 pmol) upon the treatment with 30 microM CPZ under the same conditions. It has been shown earlier, that dCTP can be used as well as CTP for biosynthesis of phospholipids. Thus, the separation of the corresponding ribo- and deoxyribo-liponucleotides was developed. CPZ almost completely inhibited the synthesis of both dCDP-EA and dCDP-Ch under the same conditions The synthesis of the activated liponucleotide precursors, can be measured by incorporation of extracellular 14C-dCyt into both dCDP-EA and dCDP-Ch, as shown earlier. While the cationic deoxyribo-liponucleotide content (dCDP-Ch, dCDP-EA) was decreased, the labelling of the anionic phospholipid precursor dCDP-diacylglycerol (dCDP-DAG) was enhanced several times, it could be labelled only in the presence of CPZ from 14C-dCyd. Thus, a principal disturbance of the membrane phospholipid synthesis is presented (i.e., inhibition of the cationic and enhancement of the anionic dCDP-DAG synthesis). This profound influence on the membrane phospholipids by chlorpromazine, might be the primary effect that contributes to the wide spectrum of CPZ effects on neuronal cells.

Deoxycytidine kinase is reversibly phosphorylated in normal human lymphocytes

The activity of deoxycytidine kinase (dCK) has been shown to be enhanced upon genotoxic stress in human lymphocytes, and reversible phosphorylation of the enzyme has been implicated in the activation process. Here, we provide compelling evidence that dCK is a cytosolic phosphoprotein. Two-dimensional gel electrophoresis revealed that dCK has several differentially charged isoforms in cells. One-third of total cellular dCK was bound to a phosphoprotein-binding column irrespective of its activity levels, indicating that other mechanisms rather than phosphorylation alone might also be involved in the stimulation of enzyme activity. We excluded the possibility that activated dCK is translocated to the nucleus, but identified a dCK isoform of low abundance with a higher molecular weight in the nuclear fractions.

Effects of intracellular calcium chelation and pifithrin-alpha on deoxynucleotide metabolism in human lymphocytes

Previously, we have found that activation of deoxycytidine kinase elicited by various DNA-damaging chemical agents could be prevented by BAPTA-AM, a cell-permeable calcium chelator or by pifithrin-alpha, a pharmacological inhibitor of p53. Here, we show that stimulation of deoxycytidine kinase by UV-light also is calcium-dependent and pifithrin-alpha-sensitive in tonsillar lymphocytes, while thymidine kinase 1 activity is stabilised in the presence of BAPTA-AM. Importantly, both UV-irradiation and calcium chelation decreased the incorporation of labelled deoxycytidine and thymidine into DNA. Pifithrin-alpha dramatically reduced the labelling of both the nucleotide and DNA fractions, possibly due to inhibition of transmembrane nucleoside transport.

Stimulation of deoxycytidine kinase results in prolonged maintenance of the enzyme activity

A number of genotoxic and antiproliferative agents such as 2-chlorodeoxyadenosine (Cladribine; CdA) and aphidicolin (APC) have been shown to stimulate the activity of deoxycytidine kinase, the main deoxynucleoside salvage enzyme in lymphocytes. Here we show that enzyme activation could be prevented by treating cells with the membrane-permeant calcium chelator BAPTA-AM. Long-term incubations demonstrated that CdA and APC not only stimulated but also sustained deoxycytidine kinase activity in the cellular context, as compared to the control and BAPTA-AM treated enzyme activities.

Modulation of human deoxycytidine kinase activity as a response to cellular stress induced by NaF

Deoxycytidine kinase (dCK) is one of the key enzymes of deoxynucleoside salvage supplying resting lymphocytes with DNA precursors for synthesis and repair. The level of dCK activity is especially important in chemotherapy with the use of deoxynucleoside analogues like arabinosyl cytosine (Citarabid, ara-C), or 2-chloro-deoxyadenosine (Cladribine, CdA). Previous results showed that Cladribine treatment of human lymphocytes increased several fold the activity of dCK without increasing the amount of dCK protein itself (Sasvári-Székely, et al., 1998, Biochem. Pharmacol. 56, 1175), and a possible post-translational modification was suggested. This theory was further investigated using NaF as an inhibitor of protein phosphatases. It was shown that NaF treatment of cells elevated dCK activity while inhibiting DNA synthesis. The possible mechanism of dCK activation/inactivation induced by exposure of cell cultures to different agents is discussed.

Analysis of mutations in the plasma cholinesterase gene of patients with a history of prolonged neuromuscular block during anesthesia

Decreased activity of plasma cholinesterase is responsible for prolonged apnea during anesthesia using neuromuscular blockers such as suxamethonium and mivacurium. More than 20 mutations have been identified so far in the BCHE gene resulting in impaired plasma cholinesterase activity. Biochemical tests are not always able to differentiate between pathological and normal sera; hence in some cases unanticipated complications can still occur during anesthesia even after measurements of enzyme activity and dibucaine numbers within the normal range. Therefore, molecular genetic testing is required for the accurate diagnosis of this deficiency. Here we present a study of plasma cholinesterase activity and BCHE genotyping of patients with a history of prolonged neuromuscular block and most of their pedigrees. All four exons of the BCHE gene were directly sequenced from samples and a number of mutations responsible for the reduction of plasma cholinesterase activity were identified. In most cases the atypical mutation in exon 2 (nt 209A --> G, Asp70 --> Gly) was found together with the K-variant mutation in exon 4 (nt 1615G --> A, Ala539 --> Thr), which is in good agreement with previous data suggesting that these mutations along with two others (at nt -116 and nt 1914) are in linkage disequilibrium.

Prenatal diagnosis of steroid 21-hydroxylase deficiency by allele-specific amplification

OBJECTIVE

Congenital adrenal hyperplasia due to steroid 21-hydroxylase deficiency (21-OHD) is the most common cause of ambiguous genitalia in females at birth. Here, we report the first prenatal diagnosis of 21-OHD by DNA analysis in Hungary.

METHODS

Allele-specific amplification (ASA) of the DNA obtained by chorionic villus sampling was performed.

RESULTS

The fetus had a homozygous nonsense mutation (Gln318Stop), suggesting a salt-wasting phenotype. Dexamethasone treatment of the mother was started on the 8th gestational week and, as the fetus was an affected female, it was continued until term. The newborn had normal external genitalia at birth, and severe salt-wasting crisis and postnatal virilization was prevented by mineralo- and glucocorticoid replacement therapy.

CONCLUSION

21-OHD was genotyped by ASA, and virilization of the fetus was prevented by antenatal dexamethasone therapy.

Genotyping the -521C/T functional polymorphism in the promoter region of dopamine D4 receptor (DRD4) gene

The -521C/Tsingle nucleotide polymorphism (SNP) in the promoter region of the dopamine D4 receptor gene (DRD4) has recently been detected in oriental (Japanese) individuals and related to novelty seeking and schizophrenia. Here, we report the analysis of the -521C/T polymorphism in a Caucasian (Hungarian) population using two independent genotyping methods. The polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) procedure utilized the Fspl restriction site around the -521 position. An additional, nonpolymorphic cleavage site was also included into the amplified region to serve as an internal standard for verifying the completion of the digestion. As another independent method, a tetraprimer system for single-tube allele-specific PCR (SAS-PCR) was developed to generate -521C and -521T specific PCR products with different fragment sizes. Consequently, genotyping with SAS-PCR is based on the gel-electrophoretic separation of the allele-specific double-stranded DNA (dsDNA) fragments. 119 healthy Hungarian individuals were genotyped for -521C/T polymorphism of the dopamine D4 promoter region, using both methods. Similar allele frequencies were found (-521C allele: 0.43; -521T allele: 0.57) as reported earlier for the Japanese population.

Modulation of human deoxycytidine kinase activity as a response to cellular stress induced by NaF

Deoxycytidine kinase (dCK) is one of the key enzymes of deoxynucleoside salvage supplying resting lymphocytes with DNA precursors for synthesis and repair. The level of dCK activity is especially important in chemotherapy with the use of deoxynucleoside analogues like arabinosyl cytosine (Citarabid, ara-C), or 2-chloro-deoxyadenosine (Cladribine, CdA). Previous results showed that Cladribine treatment of human lymphocytes increased several fold the activity of dCK without increasing the amount of dCK protein itself (Sasvári-Székely, et al., 1998, Biochem. Pharmacol. 56, 1175), and a possible post-translational modification was suggested. This theory was further investigated using NaF as an inhibitor of protein phosphatases. It was shown that NaF treatment of cells elevated dCK activity while inhibiting DNA synthesis. The possible mechanism of dCK activation/inactivation induced by exposure of cell cultures to different agents is discussed.

Activation of deoxycytidine kinase by inhibition of DNA synthesis in human lymphocytes

Deoxycytidine kinase (dCK, EC.2.7.1.74) is a key enzyme in the intracellular metabolism of 2-chlorodeoxyadenosine, 1-beta-D-arabinofuranosylcytosine, difluorodeoxycytidine, and other drugs used in chemotherapy of different leukaemias and solid tumours. Recently, stimulation of dCK activity was shown by these analogues and by other genotoxic agents such as etoposide and NaF, all of which cause severe inhibition of DNA synthesis in cell cultures. Here we describe that direct inhibition of DNA polymerases by aphidicolin stimulated dCK activity in normal lymphocytes and acute myeloid leukaemic cells, as well as in HL 60 promyelocytic cell cultures. Increased dCK activity was not due to new protein synthesis under our conditions, as measured by immunoblotting. Partial purification by diethylaminoethyl-Sephadex chromatography revealed that the activated form of dCK survived purification procedure. Moreover, it was possible to inactivate purified dCK preparations by recombinant protein phosphatase with Ser/Thr/Tyr dephosphorylating activity. These data suggest that the activation of dCK may be due to phosphorylation, and that deoxynucleoside salvage is promoted during inhibition of DNA synthesis in human lymphocytes.

Differences in thermostability of thymidine kinase isoenzymes in normal ovary and ovarian carcinoma

Thymidine kinase 1 (TK 1 EC. 2.7.1.21) the most specific and cell-cycle regulated salvage enzyme for pyrimidine nucleoside supply of DNA synthesis is a promising target to rationally designed chemo- and other therapies. The present study was undertaken to compare the heat stability of TK isoenzymes of both normal ovarian and epithelial ovarian cancer cells. Tissue extracts of epithelial ovarian carcinomas (N = 7) and normal ovaries (N = 9) were analyzed for thymidine kinase activity using the polyethyleneimine-cellulose disc radioassay. The TK activity in extracts of ovarian carcinomas was 12-fold higher than in extracts of normal ovaries. The TK activity of ovarian carcinomas decreased significantly even after 30 minutes incubation at 37 degrees C while, the enzyme activity of normal ovarian extracts was more stable and decreased to the same extent after 120 minutes. The half-life time of the enzyme activity was 82 min in the normal but only 36 minutes in the cancer tissue extract at 37 degrees C.

CONCLUSION

The TK activity of malignant ovarian cells was much higher but more unstable (t1/2 = 36 minutes) than the enzyme isolated from healthy ovaries (t1/2 = 82 minutes). This profound difference in thermostability might provide the molecular background for hyperthermia combined with chemotherapy as a promising treatment for ovarian malignancies.

Association between Novelty Seeking and the -521 C/T polymorphism in the promoter region of the DRD4 gene

Association between the human personality trait 'Novelty Seeking' and the polymorphism of the DRD4 gene was first reported by Ebstein and Benjamin in 1996. This was soon followed by replication studies in various ethnic groups and by studying the role of other neurotransmitter receptor and transporter genes in the genetic determination of human temperament. More recently, several polymorphic sites of the upstream regulatory region of the DRD4 gene have been described. Among these the -521 C/T single nucleotide polymorphism (SNP) was shown to be associated with the Novelty Seeking (NS) scores of the Temperament and Character Inventory (TCI) in a Japanese male population. We have investigated the -521 C/T SNP polymorphism in a Caucasian (Hungarian) population, and here we report a replication of the Japanese findings, in an association study involving 109 healthy Hungarian volunteers. We found a weak association between NS and CC vs CT or TT genotypes (P < 0.06). Examination of this relation in male and female sex groups, however, strengthened the association for females (P < 0.01), but showed no genotypic effect for males.

Rapid and sensitive genotyping of dopamine D4 receptor tandem repeats by automated ultrathin-layer gel electrophoresis

Prior studies have revealed possible association between the presence of a seven repeat of the 48 bp variable number tandem repeat polymorphism of the human dopamine D4 receptor gene (DRD4) and some normal and pathological human traits, such as novelty seeking, hyperactivity disorders, and substance abuse. Some reports supported this finding whereas others did not. Incorrect genotyping could be one of the reasons for these controversial results, and might originate from preferential amplification of shorter polymerase chain reaction (PCR) products, resulting in the so-called allele dropout. In this paper we optimized the conditions for simultaneous amplification of shorter and longer amplicons of the 48 bp repeat region of the DRD4 gene in order to avoid the loss of the longer allele and consequent incorrect genotyping, using very low DNA template concentrations and partial replacement of 2'-deoxyguanosine-5'-triphosphate (dGTP) by 2'-deoxyinosine-5'-triphosphate (dITP). The optimized PCR method in combination with high throughput automated ultrathin-layer gel electrophoresis was suitable for rapid genotyping from less than a nanogram DNA using noninvasive sampling (buccal epithelial cells). All detected genotypes are presented, including such rear heterozygotes as the 2 x and 8 x 48 bp repeats in the same sample, showing the reliability of our novel detection method of longer alleles in the presence of shorter alleles.

Rapid genotyping of factor V Leiden mutation using single-tube bidirectional allele-specific amplification and automated ultrathin-layer agarose gel electrophoresis

We report a novel, high-throughput genotyping method by single nucleotide polymorphism (SNP) analysis using bidirectional allele-specific amplification with polymerase chain reaction (PCR) in a single-step/single-tube format. Blood coagulation factor V G1691A (also referred to as Leiden) mutation was chosen as a model system for SNP detection, as this is one of the most common inherited risk factors of thrombosis, effecting 2-5% of the human population. The rationale of our method is the production of allele-specific PCR fragments, different in size, which was achieved by bidirectional amplification, starting from the position of the mutation. Thus, both homozygosity and heterozygosity were readily identified from a single reaction by simply determining the sizes of the resulting PCR products. The advantage of our assay, compared to other single-tube systems, is that this method did not require the use of pre-PCR labeled (fluorophore) primers or probes. Preferential production of the allele-specific products was achieved by a hot-start, time release PCR system. Specificity was increased by introducing a mismatch in the 3'-antepenultimate position of the allele-specific primers. This method made possible the large-scale screening for the factor V Leiden mutation using single-tube PCR followed by automated ultrathin-layer agarose gel electrophoresis, with real-time detection of the "in migratio" ethidium-bromide-labeled fragments.

Rapid genotyping of factor V Leiden mutation using single-tube bidirectional allele-specific amplification and automated ultrathin-layer agarose gel electrophoresis

We report a novel, high-throughput genotyping method by single nucleotide polymorphism (SNP) analysis using bidirectional allele-specific amplification with polymerase chain reaction (PCR) in a single-step/single-tube format. Blood coagulation factor V G1691A (also referred to as Leiden) mutation was chosen as a model system for SNP detection, as this is one of the most common inherited risk factors of thrombosis, effecting 2-5% of the human population. The rationale of our method is the production of allele-specific PCR fragments, different in size, which was achieved by bidirectional amplification, starting from the position of the mutation. Thus, both homozygosity and heterozygosity were readily identified from a single reaction by simply determining the sizes of the resulting PCR products. The advantage of our assay, compared to other single-tube systems, is that this method did not require the use of pre-PCR labeled (fluorophore) primers or probes. Preferential production of the allele-specific products was achieved by a hot-start, time release PCR system. Specificity was increased by introducing a mismatch in the 3'-antepenultimate position of the allele-specific primers. This method made possible the large-scale screening for the factor V Leiden mutation using single-tube PCR followed by automated ultrathin-layer agarose gel electrophoresis, with real-time detection of the "in migratio" ethidium-bromide-labeled fragments.

Treatment of normal and malignant cells with nucleoside analogues and etoposide enhances deoxycytidine kinase activity

Deoxycytidine kinase (dCK), one of the rate-limiting enzymes in the intracellular metabolism of many antileukaemic drugs, was shown to be stimulated after treatment of human tonsillar lymphocytes by 2-chloro-2'-deoxyadenosine (cladribine, CdA) (Sasvári-Székely, et al., Biochem Pharmacol 1998, 56, 1175-1179). Here we present a comparative study of different normal and malignant cells in respect to the activation of dCK by CdA. G-phase lymphocytes showed a higher sensitivity for dCK stimulation than S-phase cells. Normal and leukaemic peripheral blood mononuclear cells, as well as the promyelocytic cell line HL60 responded to CdA treatment by a 2-5-fold increase in activity of dCK. However, no significant stimulation was detected either in CCRF-CEM T-lymphoblastoid cells, or in K562 myeloid cells. Thymidine kinase (TK) activity was not stimulated in any cases. Treatment of these cells with several other analogues beside CdA, such as 2-chloro-2'-arabino-fluoro-2'-deoxyadenosine (CAFdA), 2-fluoro-1-beta-D-arabinosyladenine (Fludarabine, FaraA) and 1-beta-D-arabinosylcytosine (cytarabine, araC) gave similar results to CdA treatment. Enhancement of dCK activity could also be achieved with the topoisomerase II inhibitor, etoposide. In contrast, 2-chloro-riboadenosine (CrA) had no effect on the dCK at concentrations of 10 microM or less, while dCyd and 5-aza-dCyd caused slight inhibition. These results indicate that treatment of cells with several inhibitors of DNA synthesis potentiates the dCK activity. The drugs widely differ in their stimulatory effect on dCK, and there are also 'responsive' and 'non-responsive' cells with respect to dCK activation. Thus, enhancement of the dCK activity by specific drugs in 'responsive' cells might give a rationale for combination chemotherapy.

Screening for mutations of 21-hydroxylase gene in Hungarian patients with congenital adrenal hyperplasia

Congenital adrenal hyperplasia (CAH) is a group of autosomal recessive disorders, causing impaired secretion of cortisol and aldosterone from the adrenal cortex, with subsequent overproduction of adrenal androgens. The most common enzyme defect causing CAH is steroid 21-hydroxylase deficiency. To determine the mutational spectrum in the Hungarian CAH population, the CYP21 active gene was analyzed using PCR. A total of 297 Hungarian patients with 21-hydroxylase deficiency are registered in the 2nd Department of Pediatrics, Budapest, Hungary, and their clinical status was evaluated. Blood samples for CYP21 genotype determination could be obtained from 167 patients (representing 306 unrelated chromosomes and 56.2% of the total group of patients). Eight of the most common mutations were screened [In2 (intron 2 splice mutation), I172N, Del (Del: apparents large gene conversion), Q318X, R356W, 1761Tins, ClusterE6, V281L] using allele-specific amplification. The most frequent mutation in the Hungarian CAH population was found to be In2. Our results have shown a good genotype/phenotype correlation in case of most mutations; the In2 mutation is associated mostly with the severe form of the disease, whereas I172N was expressed in a wide spectrum of phenotypes. 1999)

[Uric acid as a scavenger in oxidative stress]

Uric acid, the naturally occurring product of purine metabolism, is widely used as a diagnostic parameter in different diseases. The concentration of uric acid may vary between broad ranges without causing symptoms, like idiopathic hyperuricemia, which behind metabolic disorders were always suggested. Recently the uric acid has been shown as a strong scavenger of oxidative stress molecules or radicals. Uric acid was successfully used to treat experimental allergic encephalomyelitis, the mouse model of multiple sclerosis (M. S.). It was shown, that patients with multiple sclerosis had significantly lower levels of serum uric acid than the control persons. In addition, statistical evaluation of more than 20 million patient records for the incidence of MS and hyperuricemic gout revealed, that the hyperuricemia may protect against MS.

Activation of deoxycytidine kinase during inhibition of DNA synthesis by 2-chloro-2'-deoxyadenosine (Cladribine) in human lymphocytes

Deoxycytidine kinase (dCK, EC.2.7.1.74), a key enzyme in intracellular metabolism of many antileukemic drugs, was shown to be activated during treatment of lymphocytes by 2-chloro-2'-deoxyadenosine (Cl-dAdo, cladribine), a potent inhibitor of DNA synthesis. While 5-[3H]-thymidine (TdR) incorporation into DNA was decreased by 80-90%, dCK activity was doubled as a consequence of incubating the cells with 1 microM 2-chloro-2'-deoxyadenosine. Thymidine kinase (dTK, EC.2.7.1.21) activity was slightly decreased under the same conditions, similarly to 5-[3H]-thymidine incorporation. dCK activation could not be prevented by cycloheximide, and neither the amount of dCK protein nor its mRNA level was increased after 2-chloro-2'-deoxyadenosine treatment. These results suggest a post-translational activation of dCK protein during inhibition of DNA synthesis.

Deoxycytidine kinase can be also potentiated by the G-protein activator NaF in cells

Recently, it has been shown, that 2-Chloro-deoxyadenosine (1), a series of analogues, and other DNA synthesis inhibitors, increased the deoxycytidine kinase (dCK) enzyme activity in different cells, without influencing thymidine kinase isoenzymes (TK1, TK2), dCMP-deaminase and thymidylate synthase (TS) activities (2,3). The dCK activity was 2-4 times higher in analogue treated cells, than in controls, which can not be explained by metabolic pool imbalance induced by the drugs. New mRNA and protein synthesis of dCK could not be detected, thus post-translational modification has been suggested for potentiation the activity of the dCK (1). Because secondary modifications of enzymes usually involve the signalling processes in cells, the universal G-protein activator fluorine ions were tested. dCK activity of human lymph node lymphocytes were increased 2-times, if cells were incubated in the presence of NaF for 1-2 hrs in cultures, while TK activity was not changed. The formation of dUTP from dCyd, was also enhanced by NaF, in parallel of dCK potentiation.

Activation of deoxycytidine kinase by various nucleoside analogues

The effect of different nucleoside analogues on deoxycytidine kinase (dCK) and thymidine kinase (TK) was compared in normal human lymphocytes and various leukemic cell lines. G-phase enriched tonsilar lymphocyte subpopulation treated by CdA showed more profound stimulation of dCK activity than S-phase cells. No substantial changes in TK activity were detected. CdA treatment increased the activity of dCK 4-fold in peripheral blood mononuclear cells (PBMC) and 2-fold in promyelocytic cell line HL60, too. However, no significant stimulation was detected either in CCRF-CEM or in K562 cell lines. 2-Cl-2'deoxy-2'F-adenine arabinoside (CAFdA), 2F-adenine arabinoside (F-araA) and cytosine arabinoside (AraC) had the same effect as CdA, although higher concentrations were needed for maximal activation. In contrast, treatment by dCyd caused slight inhibition of dCK. The possibility of interference of nucleoside analogues with the mechanisms of posttranslational modification of dCK was proposed.

Activation of deoxycytidine kinase during inhibition of DNA synthesis in human lymphocytes

Deoxycytidine kinase was shown to be activated during 2-chlorodeoxyadenosine (CdA) treatment of human lymphocytes, under the conditions when the DNA synthesis is inhibited. As the increase of dCK activity was shown in crude protein extracts, without an increase in the amount of dCK protein, shown by immunostaining after SDS-PAGE, a secondary modification of the protein structure was considered. NaF treatment of cells in the concentration range of 5-20 mM gave a similar activation of dCK, suggesting a possible role of phosphatases and/or a possibility of a G-protein related phenomenon. Using the same conditions, no effect of CdA or NaF was found on the thymidine kinase activity of cell extracts. Alternatively, activation of catabolic pathways could be considered, however, the increase in dCK activity was not influenced either by the removal of 5'-nucleotidases, or by the inhibition of deaminases.

Similar changes were induced by Cladribine and by gemcitabine, in the deoxypyrimidine salvage, during short-term treatments

Short term treatments (1-2 hrs) of human tonsillar lymphocytes by Cladribine (2-Chloro-deoxyadenosine, CdA) have suggested a new target for CdA, the inhibition of dCMP deaminase (Sasvári et al. 1994; BBRC 203, 1378). Further investigations have shown, that the dCMP-deaminase activity could be inhibited by 2-Cl-dAMP in cell free extracts of lymphocytes. The pool size of dUMP (measured by an antibody against dUMP) was also decreased in WiDr colon cancer cells by CdA. The new antimetabolite against solid tumours, Gemcitabine (2',2'-difluoro-deoxycytidine, dFdC), had similar effects on the salvage of thymidine (dThd) and deoxycytidine (dCyd) as CdA. The Ki values for 3H-dThd and 3H-dCyd incorporation into DNA were 0.16 uM and 1.0 uM dFdC, respectively. The labeling of the TTP pool increased 6-7 times, while of dCTP pool only 1.5-1.7 times, suggesting a decrease of the size of corresponding pools. Similarly to CdA, the labeling as well as the concentration of dUMP was also decreased by dFdC. Both analogues are able to increase the deoxycytidine kinase activity, necessary for their phosphorylation and therapeutic action in cells. The target(s) for the two different drugs seems to be common.

Effect of site-directed mutagenesis of the arginine residues 509 and 748 on mouse band 3 protein-mediated anion transport

Using site-directed mutagenesis, the arginine residues 509 and 748 in mouse band 3 protein were substituted by Lys, Thr, and Cys, or by Lys and Gln, respectively. After expression in Xenopus oocytes of the cRNAs encoding wild type band 3 or any one of the band 3 mutants, chloride equilibrium exchange was measured. When the flux measurements were performed two to three days after microinjection of the cRNAs, in contrast to the wild type, neither one of the mutants was able to accomplish transport, with the possible exception of the mutants R509K and R748K both of which showed some transport activity of doubtful significance. Immunoprecipitates revealed that the Arg 748 mutants were expressed similar to the wild type band 3 while no expression of the Arg 509 mutants could be detected. When the flux measurements were performed only 3 h after microinjection of the cRNAs, transport activity was observed in the oocytes that had received cRNAs encoding wild type band 3. In some oocytes of a population, a very slight transport activity was brought about by cRNA encoding Arg 509 mutants. No transport activity could be detected after injection of the Arg 748 mutant. Immunoprecipitation demonstrated the successful biosynthesis of wild type band 3 and of both the Arg 509 and the Arg 748 mutants. The experiments suggest that mutation of Arg 748 leads to biosynthesis of an inactive form of the band 3 protein, while that of Arg 509 results in expression of an abnormally folded, possibly functionally more or less intact form, which is proteolytically degraded within less than one day.

Software assessment under consideration of validation aspects: PPS and PMS systems

Due to safety aspects, business risks and regulations of the FDA [FDA, 1983, Guide to Inspection of Computerized Systems in Drug Processing. USA] and the EU [EU-Leitfaden einer Guten Herstellpraxis for Arzneimittel, 1989, III/2244/87 Rev. 3. Jan. 1989], computer based systems used in the pharmaceutical production have to be validated. In this paper we assessed which modules of production planning and control (PPS) and production management systems (PMS) have to be validated using a risk analysis procedure. It could be shown that the necessity of the validation concerns, above all, the modules of production management systems. Furthermore, a software supplier questionnaire was developed according to the V-model of Royce [National Computing Centre, 1989. STARTS Publications, UK.]. The software supplier questionnaire was applied on four software products, which are mostly used in the pharmaceutical industry. Although these were developed according to a life cycle concept they fulfil the validation requirements, measured with the developed questionnaire, to a different degree. Especially the key element of the risk analysis was differently interpreted.

Human tonsillar lymphocytes as targets for immunosuppressive and anticancer drugs

As has been shown earlier by us, the metabolism of extracellular deoxycytidine (dCyd) is 2-3 times higher in follicular and in PNA+ cells than in other cells. Deoxycytidine kinase (dCK) is one of the most important target enzymes for anti-proliferative drugs such as arabinosile-cytosine (ara-C), 2-Cl-deoxyadenosine (CdA). Neither the dCK activity nor the polypeptide correlates with the S phase of the cells, as thymidine kinase (TK1) does in tonsils. The newly developed anti-leukemic drug CdA, and also BrdA, are also phosphorylated by dCK and both effectively inhibit the 3H-dThd incorporation into DNA in tonsillar lymphocytes. A new molecular mechanism has been developed for CdA; it inhibits the interconversion of dCyd into dThd nucleotides. Analysis of the pools after 3H-dCyd labeling showed a decrease of the dUMP labeling. The inhibition of dCMP deaminase by the corresponding monophosphates (Cl-dAMP) in the cells has been suggested. CdA cannot be deaminated by adenosine deaminase (ADA), thus providing a good tool to investigate the importance of that enzyme during differentiation of the lymphoid cells. Elucidation of the nucleoside metabolism during the normal differentiation process might be the only way to get information about the same pathways in malignant transformations, i.e., in leukemias.

Nucleoside transport and metabolism in lymphocytes, polymorphonuclear cells and cerebral synaptosomes

The salvage of nucleosides dominates over de novo biosynthesis in lymphocytes, polymorphonuclear cells (PMN) and in central neutral nervous system (CNS) in higher organisms. Earlier works in our laboratory have shown that the salvage of deoxycytidine (dCyd) did not correlate with DNA synthesis. The uptake and metabolism of dCyd was higher in undifferentiated germinal center lymphocytes and in follicles comparing to more differentiated cells. Recently we have compared the transport of thymidine (dThd), dCyd, uridine (Urd) and adenosine (Ado) in the three cell systems in which the salvage of nucleosides is dominating. It was found that dCyd was transported 30 times more effectively into lymphocytes than into PMN and synaptosomes, while Urd was transported about the same rate into the two cells and into synaptosomes. All transport processes could be inhibited by dipyridamole, NBRPR, papaverine and dilazep. The dCyd and dThd was phosphorylated even at 0 degrees C up to TTP and dCTP without incorporation into DNA and into liponucleotides. Our results show that the processes of transport-phosphorylation, as well as the processes of DNA-CDP-phospholipid synthesis are tightly coupled to each other in intact cells and organelles.

A novel effect of the new antileukemic drug, 2-chloro-2'-deoxyadenosine, in human lymphocytes

2-chloro-2'-deoxyadenosine (Cl-dAdo) is a potent drug against hairy cell leukemia and other lymphomas. Its effects on the metabolism of labeled deoxycytidine (5-[3H]dCyd) and deoxythymidine ([3H]dThd) were investigated in short term cultures of human lymphocytes. In the presence of Cl-dAdo, a more pronounced inhibition of DNA synthesis was found, accompanied with a much higher accumulation of radioactivity in dTTP than in dCTP. This difference disappeared in the presence of exogenous dThd. Analysis of intracellular metabolites of 5-[3H]dCyd showed an increase in [3H]dCTP used for liponucleotide biosynthesis and a decrease in [3H]dUMP formation in the presence of Cl-dAdo, suggesting the possible inhibition of dCMP deaminase.

Deoxyribocytidine is salvaged not only into DNA but also into phospholipid precursors. IV. Exogenous deoxyribocytidine can be used with the same efficacy as (ribo)cytidine for lipid activation

Utilisation of exogenous (ribo)cytidine (3H-CR) and deoxyribocytidine (3H-CdR) for DNA/RNA synthesis and for activation of phospholipid intermediates was compared in human tonsillar lymphocytes. Incorporation of 3H-CdR into dCDP-choline and into dCDP-DAG was similar or even higher than labelling of CDP-choline and CDP-DAG from 3H-CR. No interconversion was found between CDP-DAG and dCDP-DAG, as shown by TLC separation of the ribo- and deoxyribocytidine derivatives. Moreover, a strict separation was found between the salvage pathways of deoxyribocytidine and (ribo)cytidine, as 4000-fold excess of non labelled (ribo)cytidine did not show any specific effect on 3H-dCDP-DAG labelling from exogenous 3H-CdR.

The salvage of deoxycytidine into dCDP-diacylglycerol by macrophages and lymphocytes

Extracellular deoxycytidine (CdR) was previously shown to be salvaged into water soluble [1] and also into lipidic [2] precursors of phospholipids in stimulated lymphocytes and in lymphoma cells [3]. In this paper we have described that non-dividing murine macrophages salvaged not only 5-3H-CdR but also tritiated thymidine (3H-TdR) mainly into the pools as nucleotides. Chlorpromazine shifted the CdR salvage into a lipidic compound of the cells which was identified as 3H-dCDP-diacylglycerol (dCDP-DAG). After 5-3H-CdR labeling the lipid/DNA ratio was eleven times higher in macrophages than in tonsillar lymphocytes. Thin layer chromatography (TLC) on borate impregnated silica gel plates gave clear separation of CDP-DAG from dCDP-DAG supporting that the extracellular precursor for it is exclusively deoxycytidine and not ribocytidine. No interconversion between deoxy- and and ribocytidine could be observed neither in lymphocytes nor in macrophages.

Compartmentation of dCTP pools disappears after hydroxyurea or araC treatment in lymphocytes

The calculated rate of DNA synthesis using [5-3H]TdR was about 4 times higher than in the case of [5-3H]CdR labeling, even after correction for the specific radioactivities of the intracellular pools. These data show a compartmentation of dCTP pools in lymphocytes. Hydroxyurea increased the specific activities of both dTTP and dCTP pools so that the calculated rate of DNA synthesis became equal. The same effect was found for araC treatment, but not for fluorodeoxyuridine. dCTP was supplied from CTP which is the lowest ribonucleotide pool in lymphocytes. Different functions of the two dCTP pools are proposed: one serving DNA replication; the other one supplies phospholipid precursors and DNA repair.

Deoxycytidine is salvaged not only into DNA but also into phospholipid precursors. III. dCOP-diacylglycerol formation in tonsillar lymphocytes

In addition to the water-soluble deoxyliponucleotides (Spasokukotskaja et al. (1988), Biochem. Biophys. Res. Commun. 155, 923), a lipid compound was shown to be labeled from external 3H-deoxycytidine (5-3H-CdR) in infant tonsillar lymphocytes. Chlorpromazine enhanced the labeling of this compound, identified by TLC as 3H-dCDP-diacylglycerol (3H-dCOP-DAG). The deoxynucleotide salvage pathway seems to be the main source for dCDP-DAG synthesis, as hydroxyurea increased its labeling from CdR. myo-Inositol induced the disappearance of 5-3H-dCOP-DAG, suggesting its utilization for phosphatidylinositol synthesis. 3H-Arabinosyl-Cytosine (araC) is also incorporated into the lipidic fraction at a rate comparable to its incorporation into DNA, supporting the effect of araC on membrane functions.

Deoxycytidine is salvaged not only into DNA but also into phospholipid precursors. II. Ara-C does not inhibit the later process in lymphoid cells

dCTP formed from exogenous deoxycytidine via the salvage pathways was previously shown to serve deoxyliponucleotide synthesis in lymphocytes (Spasokukotskaja et al, Biochem. Biophys. Res. Commun. (1988) 155, 923-929) and now in lymphoma cells. After treatment with 1-beta-D-arabino-furanosylcytosine (ara-C), much more araCTP as well as araCDP-choline was formed in lymphoma cells than in lymphocytes explaining the high sensitivity of lymphoma cells to this drug. Ara-C did not inhibit labeling of 5-3H-dCDP-choline from exogenous 5-3H-deoxycytidine while inhibiting DNA synthesis. Excess of exogenous ribocytidine diminished labeling of araCDP-choline, without any effect on dCDP-choline. These data suggest that araCDP-choline and dCDP-choline were synthesized from separate pools in these cells.